https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122282
Bug ID: 122282
Summary: [target, ppc64-linux] return of small character array
not according to ABI spec
Product: gcc
Version: 14.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
Consider gdb test-case gdb.ada/return-small-char-array:
...
$ ls gdb/testsuite/gdb.ada/return-small-char-array
proc.adb value.adb value.ads
...
Compiled like so, on cfarm121 with gcc 14.3.0:
...
$ gnatmake proc.adb value.adb -g
powerpc64-linux-gnu-gcc-14 -c -g proc.adb
powerpc64-linux-gnu-gcc-14 -c -g value.adb
powerpc64-linux-gnu-gnatbind-14 -x proc.ali
powerpc64-linux-gnu-gnatlink-14 proc.ali -g
powerpc64-linux-gnu-gcc-14 -c -g value.adb
$
...
After using gdb to step into value.name, we have:
...
(gdb) p Of_Value
$1 = "abcd"
(gdb) ptype Of_Value
type = <ref> array (1 .. 4) of character
(gdb)
...
and one instruction before returning from that function, r3 has the value:
...
(gdb) p /x $r3
$3 = 0x3fffffffedb0
(gdb) p /x *$r3
$4 = 0x61626364
(gdb)
...
Assuming that gcc intends to implement this spec (
https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html ), this is
a bug in GCC because the spec states that:
...
Character arrays of length 8 bytes or less, ... , will be returned right
justified in r3.
...
But instead, r3 is a pointer to the character array.
